The circuit breaker is the most important control device in an electrical power system, and is also a device that actions most frequently. The function of the circuit breaker is switching off and switching on the load circuit. And when a fault such as over-loading, short circuit, under-voltage and the like occurs on a circuit, the circuit breaker can automatically break the circuit, playing a role of protection, preventing the accident from becoming worse, and ensuring safe operation.
A solid state circuit breaker is a new power-electronic-device-based switch device with no break, so it has a speed of action far faster than a traditional mechanical breaker, and its time of action is at a microsecond level, which can accurately switch the circuit off or on at a specified phase of voltage or current, thus can satisfy the strict requirements of micro power grid on switch devices. With the use of a fault current limiter, the solid state circuit breaker can cut off the faulty line before the short circuit current has significantly increased, thus improving stability of the power grid largely.
However, the breaker has a higher failure rate during operation. Once a fault occurs on the breaker, it will very easily lead to a power grid accident and cause a huge economic loss.
Therefore, it is necessary to provide with a breaker with a function of fault self-diagnosing.